1. Field of the Invention
The present invention relates to an optical pickup apparatus which includes a light source unit and irradiates light from the light source unit on a recording medium to thereby record or reproduce information, and a position adjustment apparatus and a position adjustment method for adjusting a position of the light source unit.
2. Description of the Related Art
FIG. 32 is a sectional view showing an optical pickup apparatus 1 in one related art. In one related art, for example, disclosed in the Japanese Unexamined Patent Publication JP-A 2002-342945, a laser beam from a semiconductor laser 2 is guided to an objective lens 4 via a collimator lens 3 opposed to the semiconductor lens 2. The semiconductor lens 2 is held by a laser holder 5, and a spherical seat 6 is interposed between this laser holder 5 and a housing 7.
The laser holder 5 and the spherical seat 6 are brought into abutment against each other on surfaces 5a and 6a which are formed in a spherical shape. In addition, the spherical seat 6 is brought into abutment against the housing 7 on the opposite side of the laser holder 5. The spherical seat 6 and the housing 7 are brought into abutment against each other on surfaces 6b and 7a which are formed in a plane shape. The surfaces 6b and 7a of the spherical seat 6 and the housing 7 are perpendicular to an axis of the collimator lens 3.
By sliding the spherical seat 6 with respect to the housing 7, a position of the semiconductor laser 2 with respect to the housing 7 is displaced such that an axis L3 of the collimator lens 3 passes a light-emitting portion 2a of the semiconductor laser 2. In addition, by sliding the laser holder 5 with respect to the spherical seat 6, tilt adjustment for adjusting a tilt of an optical axis of the laser beam with respect to the axis L3 of the collimator lens 3 is performed.
FIG. 33 is a sectional view showing an optical pickup apparatus 10 in another related art. In another related art, for example, disclosed in the Japanese Unexamined Patent Publication JP-A 2000-36117, a laser beam from a semiconductor laser 11 is guided to an objective lens 13 via a coupling lens 12 opposed to the semiconductor laser 11. The optical pickup apparatus 10 includes a laser holder 14, in which the semiconductor laser 11 is provided, and a housing 17, which includes a housing main body 15 and a main body side portion 16. The laser holder 14 and the housing main body 15 are brought into abutment against each other on surfaces 14a and 15a which are formed along one imaginary cylindrical surface.
The housing main body 15 is aligned with respect to the main body side portion 16 in advance such that an axis of the one imaginary cylindrical surface is perpendicular to an axis of the coupling lens 12 in a state in which the laser holder 14 is brought into abutment against the housing main body 15. In addition, an engagement portion (not shown), which engages with a rotation jig such as an eccentric pin, is provided in the laser holder 14. This engagement portion is engaged with the rotation jig. By operating the rotation jig, the laser holder 14 is slid with respect to the housing main body 15. Consequently, the optical axis of the laser beam is angularly displaced around the axis of the one imaginary cylindrical surface, and the tilt adjustment is performed.
In the above-mentioned the related art, in order to adjust a position of the optical axis of the laser beam, the two members of the laser holder 5 and the spherical seat 6 are displaced with respect to the housing 7. Moreover, in the above-mentioned another related art, in order to adjust a position of the optical axis of the laser beam, an adjustment mechanism, which slides and adjusts the laser holder 14 with respect to the housing 17 by engaging the rotation jig and the engagement portion of the laser holder 14 to operate the rotation jig, is used. Therefore, in the respective related arts, adjustment work and a constitution of the apparatus are complicated, which also makes adjustment equipment complicated. In particular, in the tilt adjustment, the surfaces 5a and 6a of a spherical shape and the surfaces 14a and 15a along one imaginary cylindrical surface are brought into sliding contact with each other. In such a constitution, in order to realize smooth tilt adjustment, depending upon curvatures of the respective surfaces, it is necessary to change the constitution by, for example, forming at least one of the members, which are slid with respect to each other, of a material with a high sliding property or applying surface processing to at least one of the members such that a high sliding property can be obtained. This requires time and labor.
In addition, in the case in which the tilt adjustment is performed, in order to align the optical axis of the laser beam with the axes of the lenses opposed to the light sources 2 and 11, it is desired that the semiconductor lasers 2 and 11 are arranged in positions where the axes of the opposed lenses pass the light-emitting portions 2a and 11a. However, the light-emitting portions 2a and 11a are not always in ideal positions in terms of design depending upon component accuracy and the like. In particular, in the above-mentioned another related art, in the case in which a position of the light-emitting portion 11a deviates, the optical axis and the axis of the coupling lens 12 cannot be aligned.
Moreover, in adjusting a position of the optical axis, in the above-mentioned related art, the two members, the laser holder 5 and the spherical seat 6, are required with respect to the housing 7 to be a reference. In the above-mentioned another related art, the two members, the laser holder 14 and the housing main body 15, are required with respect to the main body side portion 16 to be a reference. Therefore, in addition to the complicated adjustment work, the number of components increases, which causes. an increase in costs.